Observation of a coronal transient from 1.2 to 6 solar radii

We describe in detail the eruptive prominence associated coronal mass ejection of August 5, 1980, as seen in both the Solar Maximum Mission (SMM) coronagraph polarimeter and the Mauna Loa Observatory (MLO) K coronameter and prominence monitor. This event gives us the first detailed look at the propagation of a “depletion” transient into the outer corona. The event begins in the MLO K coronameter as a rising depletion of material, but appears later in the SMM coronagraph as an ordinary coronal mass ejection with a three‐part structure: a bright core within a dark lunette surrounded by a bright featureless “loop.” A joint time‐height plot of the major structures of the eruption seen by both instruments suggests that we can associate the three‐part structure in the outer corona with features in the low corona (prominence, prominence cavity, outer bright front). We argue from its observed mass that the leading loop in the SMM field of view is probably material that was in the background corona before the event. We suggest that this material has been displaced and set into motion by the rising “cavity.” One “leg” of the transient as seen by the SMM instrument is strongly bowed away from the bright core or prominence; this is in contrast to the straight, radial legs seen after Skylab mass ejections.